265
FXPQ50 PGUM 070752
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
552 PM ChST Fri Jun 7 2024

.Marianas Synopsis...
Satellite imagery shows few to isolated showers across the Marianas
this afternoon. Latest altimetry data shows combined seas of 4 to 6
feet. This is corroborated with Ritidian buoy ranging from 5 to 6
feet today.

&&

.Discussion...
Only slight changes to the forecast was made. Latest GFS time-height
supports an earlier onset of scattered showers for Guam beginning
during the day on Sunday. A model blend of the GFS and ECMWF with the
previous forecast also supports this timing. Further north, the
time-height for Saipan shows slightly drier conditions through the
day on Sunday at the 700 to 500mb level. Thus, isolated showers were
maintained until Sunday night. Similarly, the onset of thunderstorms
begins Sunday night for Guam and Rota and Wednesday night for Saipan
and Tinian. This is supported by the differences in the time-height
charts. The zone forecast was split for this package to cover the
differences. The last few GFS runs have been trending wetter for Guam
and Rota next week, with the ECMWF remaining consistent with a
similar amount of QPF. Trends will need to be monitored for
opportunities to increase PoPs through next week. Stay tuned for
future updates.

&&

.Marine...
Combined seas of 4 to 6 feet will diminish further to between 3 and
5 feet around Saturday. East winds of 10 to 15 knots will diminish to
between 5 and 10 knots around Saturday night. Thunderstorms will be
possible Sunday night for Guam and Rota coastal waters.

&&

.Eastern Micronesia...
Satellite shows an active Inter-Tropical Convergence Zone (ITCZ)
across eastern Micronesia. A broad weak circulation is seen south of
the ITCZ southwest of Pohnpei, with a trough extending eastward to
near 170E. The ITCZ looks to be the main player for the next few
days across the region while the circulation and trough look to
enhance convection mainly south of the main islands. Latest model
guidance indicates the ITCZ will go through periods of weakening and
strengthening through the weekend as it waves north and south. The
ITCZ looks to move out of the Marshalls over the weekend. This will
result in mostly scattered showers and isolated thunderstorms through
Saturday for Majuro and until Monday for Pohnpei and Kosrae. By
early next week, the ITCZ looks to break down, with mostly isolated
showers expected across eastern Micronesia for a short time. Majuro
will see a return in increased convection Monday night as the first
of a series of weak trade-wind troughs move into the area. These
troughs will transit across eastern Micronesia, bringing periods of
increased convection to Kosrae beginning Tuesday evening and to
Pohnpei by Wednesday.

Marine conditions look to remain fairly benign over the next several
days, with seas of 3 to 5 feet across the region, with up to 6 feet
possible at times for Majuro. Light to gentle winds will prevail,
with Majuro seeing occasional moderate trades.

&&

.Western Micronesia...
A broad trough is seen over Yap and Palau with a weak circulation
south of Koror and converging surface winds southeast of Yap. On and
off scattered showers are expected the next few days for Koror and
for Yap on and off scattered starting Saturday evening. A day or two
or fairer weather is expected late Sunday through Monday as a ridge
moves through, but with light and variable winds we may see island
effect showers and thunderstorms.

Southeast of Chuuk, clouds and showers are seen developing across an
area of convergent winds on the north side of a weak circulation.
Expect this feature to weaken and broaden tonight then shift south,
most likely bringing an uptick in showers to Chuuk Saturday evening.
Around Monday, a trade-wind trough is expected to bring an increase
in showers.

Yap buoy is reporting combined seas of near 4 feet and altimetry data
near Palau and Yap showed combined seas around 2 and 4 feet. Expect
similar conditions through next week. Light winds are expected to
continue through early next week at Yap, and Palau and light to
gentle for Chuuk.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
MP...None.
Marianas Waters...None.
&&

$$

Marianas: Williams
Eastern Micronesia: Kleeschulte
Western Micronesia: Hong